Method and apparatus for irradiating a microlithographic substrate

ABSTRACT

A method and apparatus for exposing a radiation-sensitive material of a microlithographic substrate to a selected radiation. The method can include directing the radiation along a radiation path in a first direction toward a reticle, passing the radiation from the reticle and to the microlithographic substrate along the radiation path in a second direction, and moving the reticle relative to the radiation path along a reticle path generally normal to the first direction. The microlithographic substrate can move relative to the radiation path along a substrate path having a first component generally parallel to the second direction, and a second component generally perpendicular to the second direction. The microlithographic substrate can move generally parallel to and generally perpendicular to the second direction in a periodic manner while the reticle moves along the reticle path to change a relative position of a focal plane of the radiation.

CROSS-REFERENCE TO RELATED APPLICATION

This application relates to material disclosed in U.S. Application No.______ (attorney docket number 10829.8547US), titled “Method andApparatus for Controlling Radiation Beam Intensity Directed toMicrolithographic Substrates,” filed on Aug. 30, 2001 and incorporatedherein in its entirety by reference.

BACKGROUND

The present invention is directed toward methods and apparatuses forirradiating a microlithographic substrate, and in particular, methodsand apparatuses for irradiating the microlithographic substrate whilemoving it axially relative to a radiation source. Microelectronicfeatures are typically formed in microelectronic substrates (such assemiconductor wafers) by selectively removing material from the waferand filling in the resulting openings with insulative, semiconductive,or conductive materials. One typical process includes depositing a layerof radiation-sensitive photoresist material on the wafer, thenpositioning a patterned mask or reticle over the photoresist layer, andthen exposing the masked photoresist layer to a selected radiation. Thewafer is then exposed to a developer, such as an aqueous base or asolvent. In one case, the photoresist layer is initially generallysoluble in the developer, and the portions of the photoresist layerexposed to the radiation through patterned openings in the mask changefrom being generally soluble to become generally resistant to thedeveloper (e.g., so as to have low solubility). Alternatively, thephotoresist layer can be initially generally insoluble in the developer,and the portions of the photoresist layer exposed to the radiationthrough the openings in the mask become more soluble. In either case,the portions of the photoresist layer that are resistant to thedeveloper remain on the wafer, and the rest of the photoresist layer isremoved by the developer to expose the wafer material below.

The wafer is then subjected to etching or metal disposition processes.In an etching process, the etchant removes exposed material, but notmaterial protected beneath the remaining portions of the photoresistlayer. Accordingly, the etchant creates a pattern of openings (such asgrooves, channels, or holes) in the wafer material or in materialsdeposited on the wafer. These openings can be filled with insulative,conductive, or semiconductive materials to build layers ofmicroelectronic features on the wafer. The wafer is then singulated toform individual chips, which can be incorporated into a wide variety ofelectronic products, such as computers and other consumer or industrialelectronic devices.

As the size of the microelectronic features formed in the waferdecreases (for example, to reduce the size of the chips placed in theelectronic devices), the size of the features formed in the photoresistlayer must also decrease. This requires focusing the radiation impingingon the photoresist layer more sharply. However, as the radiation is moresharply focused, it loses depth of focus. As a result, only the topstratum of the photoresist layer may be adequately exposed to thesharply-focused radiation, and the lower strata of the photoresist layermay not be adequately exposed. Accordingly, the edges of those portionsof the photoresist layer that remain on the wafer after the wafer isexposed to the solvent can become indistinct. This in turn can adverselyaffect the definition of the microelectronic features formed on thewafer.

One approach to addressing the foregoing problem (a “stepper” approach)has been to expose one or more relatively large fields of the wafer tothe incoming radiation, and then move the wafer axially relative to theincoming radiation so that the focal plane of the radiation passesthrough several strata of the photoresist layer. This process isgenerally referred to as “focus drilling.” In one specific applicationof this principle (termed focus latitude enhancement exposure or“FLEX”), the wafer is placed on a stepper stage and one field of thewafer is exposed to light passing through a mask and focused at a givendepth. The focal plane is then changed to be at a different depth, andthe field is re-exposed. This process is repeated sequentially for anumber of focal plane depths. Alternatively, the wafer can be movedaxially as it is being exposed. In either case, the stepper then movesthe wafer to expose another field of the wafer and the process isrepeated until all the fields of the wafer are exposed. Further detailsof the FLEX process are disclosed in a publication titled “Improvementof Defocus Tolerance in a Half-Micron Optical Lithography by the FocusLatitude Enhancement Exposure Method: Simulation and Experiment”(Hiroshi Fukuda et al., July 1989). One drawback with the foregoingmethod is that it is performed on a stepper apparatus. Accordingly, theresolution of the features may be limited because an entire field of thewafer must be accurately imaged with each exposure.

Another approach to addressing the foregoing problem (a “scanner”approach) is to move the wafer along an inclined path as the wafer andthe mask scan past each other to align successive portions of the maskwith corresponding successive portions of the wafer passing below. U.S.Pat. No. 5,194,893 to Nishi discloses a scanner method for altering theaxial position of the depth of focus relative to the photoresist layeras the wafer moves relative to the mask. According to this method, thewafer is canted relative to the incoming radiation so that the focalplane passes through more than one strata of the photoresist layer asthe wafer and the mask move relative to each other. The scanner approachcan be more accurate than the stepper approach because only a smallportion of the mask must be imaged at any given time. However, adrawback with the foregoing approach is that it may not provide thedesired level of control over the position of the focal plane.

SUMMARY

The present invention is directed toward methods and apparatuses forexposing a radiation-sensitive material of a microlithographic substrateto a selected radiation. In one embodiment, the method can includedirecting the radiation along a reticle radiation path segment toward areticle. The method can further include passing the radiation from thereticle and to the microlithographic substrate along a substrateradiation path segment. The reticle is then moved along a reticle pathgenerally normal to the reticle radiation path segment, and themicrolithographic substrate is moved along a substrate path. Thesubstrate path has a first component generally parallel to the substrateradiation path segment and a second component generally perpendicular tothe substrate radiation path segment. The microlithographic substratemoves generally parallel to and generally perpendicular to the substrateradiation path segment toward and away from the reticle while thereticle moves along the reticle path. In a further aspect of thisembodiment, the method can include oscillating the microlithographicsubstrate toward and away from the reticle along an axis generallyparallel to the substrate radiation path segment in a periodic manner.In yet a further aspect of this method, the radiation can include a beamhaving a beam width at the microlithographic substrate and themicrolithographic substrate can be moved for one period during the timethe microlithographic substrate moves transverse to the beam by adistance of one beam width or about one beam width.

The invention is also directed toward apparatuses for exposing aradiation-sensitive material of a microlithographic substrate to aselected radiation. In one aspect of the invention, the apparatus caninclude a source of radiation positioned to direct a selected radiationalong a radiation path. The apparatus can further include a reticlepositioned in the radiation path with the reticle being configured topass the radiation toward a microlithographic substrate. The reticle iscoupled to at least one actuator to move relative to the radiation pathin a direction generally perpendicular to the radiation path. Theapparatus can further include a substrate support having a supportsurface positioned to support a microlithographic substrate in theradiation path with the microlithographic substrate receiving radiationpassing from the reticle. The substrate support can be coupled to atleast one actuator to move relative to the radiation path along asubstrate support path having a first component generally parallel tothe radiation path and a second component generally perpendicular to theradiation path. The substrate support can be movable along both thefirst and second components of the substrate support path while thereticle moves along the reticle path.

In further embodiments, the apparatus can include a substrate supporthaving a support surface positioned to support a microlithographicsubstrate in the radiation path with a surface of the microlithographicsubstrate at least approximately normal to the radiation path. Theapparatus can further include a reticle positioned in the radiation pathand oriented at a first non-normal angle relative to the radiation path.The reticle can be coupled to an actuator to move along a reticle pathinclined relative to the substrate path by a second non-normal angleapproximately equal to the first non-normal angle. Alternatively, thesubstrate support can be configured to support the microlithographicsubstrate at a first non-normal angle relative to the radiation path,and the reticle can be configured to move along a reticle path orientedat a second non-normal angle relative to radiation path.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an apparatus in accordance with anembodiment of the invention with components shown schematically.

FIG. 2 is an enlarged view of a portion of the apparatus illustrated inFIG. 1 in accordance with an embodiment of the invention.

FIGS. 3A-F are schematic illustrations of motion paths of amicrolithographic substrate in accordance with several embodiments ofthe invention.

FIG. 4 is a schematic illustration of an apparatus having an inclinedreticle that moves along an inclined motion path in accordance withanother embodiment of the invention.

FIG. 5 is a schematic illustration of an apparatus supporting amicrolithographic substrate at an incline, and a reticle that travelsalong an inclined path in accordance with yet another embodiment of theinvention.

DETAILED DESCRIPTION

The present disclosure describes methods and apparatuses forcontrollably exposing a radiation-sensitive material of amicrolithographic substrate to a selected radiation. The term“microlithographic substrate” is used throughout to include substratesupon which and/or in which microelectronic circuits or components, datastorage elements or layers, vias or conductive lines, micro-opticfeatures, micromechanical features, and/or microbiological features areor can be fabricated using microlithographic techniques. Many specificdetails of certain embodiments of the invention are set forth in thefollowing description and in FIGS. 1-5 to provide a thoroughunderstanding of these embodiments. One skilled in the art, however,will understand that the present invention may have additionalembodiments, and that the invention may be practiced without several ofthe details described below.

FIG. 1 schematically illustrates an apparatus 110 for controllablyirradiating a microlithographic substrate 160 in accordance with anembodiment of the invention. The apparatus 110 can include a radiationsource 120 that directs an electromagnetic radiation beam 128 along aradiation path 180 toward the microlithographic substrate 160.Optionally, the radiation beam 128 can pass through one or morediffractive elements 122 (two are shown in FIG. 1 as diffractiveelements 122a and 122b), and through a lens system 123 configured toshape and/or magnify the radiation emitted by the source 120.Optionally, the apparatus 110 can further include a light tube 124positioned to generate a plurality of images of the radiation source120. The light tube 124 and/or a sizing lens 125 can size the radiationbeam 128, which is then directed by a mirror 126 in a first direction181 through a focusing lens 127 and to a reticle or mask 130 along areticle radiation path segment 181 a.

The reticle 130 can include reticle apertures 131 through which theradiation passes to form an image on the microlithographic substrate160. Before the radiation reaches the substrate 160, it passes through areduction lens system 140, which reduces the image pattern defined bythe reticle 130 to a size corresponding to the size of the features tobe formed on the microlithographic substrate 160. The radiation exitingthe reduction lens system 140 travels along a substrate radiation pathsegment 182 a and impinges on a radiation-sensitive material (such as aphotoresist layer 161) of the microlithographic substrate 160 in asecond direction 182 to form an image on the layer 161. In oneembodiment, the beam 128 impinging on the layer 161 can have a generallyrectangular shape with a width of from about 5 mm. to about 8 mm. and alength of about 26 mm. at the microlithographic substrate 160. In otherembodiments, the beam 128 incident on the layer 161 can have othershapes and sizes. In one embodiment, the radiation can have a wavelengthin the range from about 157 nanometers or less (for example, 13nanometers) to a value of about 365 nanometers or more. For example, theradiation can have a wavelength of 193 nanometers. In other embodiments,the radiation can have other wavelengths, such as 248 nanometers,suitable for exposing the layer 161 on the microlithographic substrate160.

The microlithographic substrate 160 is supported on a substrate support150. The substrate support 150 moves along a substrate support path 151and the reticle 130 moves in the opposite direction along a reticle path132 to scan the image produced by the reticle 130 across the layer 161while the position of the radiation beam 128 remains fixed. Accordingly,the substrate support 150 can be coupled to a support actuator 154 andthe reticle 130 can be coupled to a reticle actuator 137. As the reticle130 moves opposite the microlithographic substrate 160, the radiationsource 120 flashes to irradiate successive portions of themicrolithographic substrate 160 with corresponding successive imagesproduced by the reticle 130 until an entire field of themicrolithographic substrate 160 is scanned. In one embodiment, theradiation source 120 can flash at a rate of about 20 cycles during thetime required for the microlithographic substrate 160 to move by onebeam width (e.g., by from about 5 mm. to about 8 mm.). In otherembodiments, the radiation source 120 can flash at other rates. In anyof these embodiments, the radiation source 120 can flash at the samerate throughout the scanning process (assuming the reticle 130 and thesubstrate support 150 each move at a constant rate) to uniformlyirradiate each field of the microlithographic substrate 160. In stillfurther embodiments, the radiation source 120 can deliver a continuousradiation beam 128.

In one embodiment, each field of the microlithographic substrate 160 cancorrespond to one or more chips or dice, and in other embodiments, thefield can have other sizes. After a field is exposed, the substratesupport 150 can “step” the microlithographic substrate 160 laterally toalign another field with the radiation beam 128, and the scan processdescribed above can be repeated until the entire microlithographicsubstrate layer 161 has been exposed to the radiation.

In a further aspect of this embodiment, a controller 170 is operativelycoupled to the reticle 130 (or the reticle actuator 137) and thesubstrate support 150 (or the support actuator 154). Optionally, thecontroller 170 can also be coupled to the reduction lens system 140.Accordingly, the controller 170 can control and coordinate the relativemovement between these elements, as described in greater detail below.

FIG. 2 is an enlarged schematic view of a portion of the apparatus 110described above with reference to FIG. 1. The radiation beam 128incident on the reticle 130 has a width W₁. The portion of the reticle130 shown in FIG. 2 has an aperture 131 with a width W₂ through whichthe radiation passes. For purposes of illustration, only one aperture131 is shown in FIG. 2, although it will be understood that the reticle130 typically includes many apertures. The reduction lens system 140reduces the size of the beam passing through the aperture 131 (forexample, by a factor of 4) so that the beam and corresponding image havea width W₃ at the layer 161 of the microlithographic substrate 160.

As the reticle 130 moves along the reticle path 132 in a directionapproximately normal to the first direction 181 of the incidentradiation, the substrate support 150 moves along the substrate supportpath 151, carrying the microlithographic substrate 160 along a parallelsubstrate path. The substrate support path 151 can have a firstcomponent 152 generally aligned with the second direction 182 of theradiation. The substrate support path 151 can also have a secondcomponent 153 generally perpendicular to the first component 152 andgenerally parallel to (but opposite) the reticle path 132.

In one aspect of the embodiment shown in FIG. 2, the first component 152of the substrate support path 151 oscillates in a periodic manner sothat the microlithographic substrate 160 moves toward and away from thereticle 130 as the reticle 130 and the microlithographic substrate 160scan past each other. Accordingly, the focal plane of the radiation beam128 impinging on the microlithographic substrate 160 can pass throughseveral depth-wise planes within the thickness of the layer 161 as themicrolithographic substrate 160 and the reticle 130 move relative toeach other. For example, the focal plane can move from a position at orproximate to an outer surface 164 of the layer 161 to a position at orproximate to an inner surface 165 of the layer 161, thereby exposing theentire thickness of the layer 161 to focused radiation. In otherembodiments, the focal plane can move axially by less than the entirethickness of the layer 161 while exposing a greater depth-wise portionof the layer 161 than is possible with a scanner apparatus having afixed focal plane.

FIGS. 3A-F include traces of the axial position of the microlithographicsubstrate 160 (on the ordinate axis) as a function of transversedistance (on the abscissa axis) for several substrate support paths 151(shown as paths 151 a-f) in accordance with several embodiments of theinvention. The ordinate axis can also represent the degree of focus fora selected plane in the layer 161 (FIG. 2), with zero indicatingcoincidence of the radiation focal plane and the selected plane of thelayer 161. The transverse distance is normalized to correspond to amovement of the microlithographic substrate 160 by one beam width W₃(FIG. 2), measured at the microlithographic substrate 160. Accordingly,a value of “1” on the abscissa axis corresponds to a movement of themicrolithographic substrate 160 by one beam width W₃.

Substrate support path 151 a is a generally sinusoidal path describing asine function. In this embodiment, the substrate support 150 and themicrolithographic substrate 160 (FIG. 2) complete one full cycle duringthe time the microlithographic substrate 160 moves by one beam width orabout one beam width (referred to hereinafter as a “normalized period”).Accordingly, the substrate support 150 moves from a neutral position toits position closest to the reticle 130, then to its position furthestfrom the reticle 130 and back to the neutral position in the amount oftime required for the microlithographic substrate 160 to move by thebeam width W₃. Path 151 b describes a modified cosine motion in whichthe substrate support 150 dwells at the position furthest from thereticle 130 for a slightly extended period of time. Path 151 c describesa straight-line triangular or saw-tooth function for which one cycle iscompleted within one normalized period.

In other embodiments, the substrate support path 151 can have othershapes. For example, path 151 d describes an approximately square wavepattern. Path 15le describes a repeated, non-sinusoidal curvilinearfunction. Path 151 f is a cosine wave that completes two cycles in onenormalized period.

In other embodiments, the substrate support path 151 can have othershapes. In a further aspect of these embodiments, the paths 151 can betailored to particular characteristics of the radiation and/or the layer161 upon which the radiation impinges. For example, (referring now toFIG. 2), it may be desirable to expose the inner strata of the layer 161(proximate to the inner surface 165) for a longer period of time thanthe outer strata (proximate to the outer surface 164). Accordingly, thetravel path 151 can “dwell” at a lower focal plane, for example, asshown in FIG. 3B by path 151 b.

In general, it may be desirable to complete an integer number of pathcycles within one normalized period to uniformly expose each successivestrip of the layer 161 in the same manner. Accordingly, the path 151 cancomplete one or two cycles in one normalized period (as shown in FIGS.3A-F), or other integer number of cycles in other embodiments.

Referring again to FIG. 2, one or more elements of the reduction lenssystem 140 can be coupled to a lens actuator 141 to move axiallyrelative to the reticle 130 and the substrate support 150 under thecontrol of the controller 170. Moving elements of the reduction lenssystem 140 can provide another degree of freedom for positioning thefocal plane of the radiation beam 128 relative to the layer 161 on themicrolithographic substrate 160. Accordingly, the reduction lens system140 can move in combination with or in lieu of moving themicrolithographic substrate 160 to vary the axial position of the focalplane relative to the layer 161.

One feature of an embodiment of an apparatus and method described abovewith reference to FIGS. 1-3F is that the microlithographic substrate 160(and the substrate support 150) can move axially relative to the reticle130 while the reticle 130 and the microlithographic substrate 160 scanpast each other. An advantage of this arrangement is that the focalplane of the radiation passing through the reticle 130 can move axiallyrelative to the layer 161 to effectively increase the depth of focus ofthe radiation and more thoroughly expose the strata of the layer 161 tothe radiation. A further advantage of this arrangement is that the axialmotion can be implemented on a scanning apparatus which, because only aportion of the reticle pattern need be focused at any point in time, canproduce microlithographic features with a higher degree of resolutionthan are available by conventional focus drilling methods.

Another feature of this arrangement is that the motion of the substratesupport 150 can follow an infinite number of controlled, periodic paths.Accordingly, the motion of the substrate support 150 can be tailored toa particular microlithographic substrate 160 or class ofmicrolithographic substrates 160. For example, if the inner portions ofthe layer 161 on the microlithographic substrate 160 require additionalexposure time, the path can be selected such that the focal plane dwellson the inner portions of the layer 161 for longer than it dwells on theouter portions.

FIG. 4 is a partially schematic illustration of a portion of anapparatus 410 that includes a substrate support 450 carrying themicrolithographic substrate 160. The apparatus 400 further includes areticle 430 oriented at a non-normal (i.e., oblique) tilt angle 433relative to a radiation beam 480 traveling along a radiation path 480 ina first direction 481. The radiation passes through the reticle 430 andthrough a reducing lens 440 to impinge on the microlithographicsubstrate 160 in second direction 482.

In a further aspect of this embodiment, the substrate support 450 andthe microlithographic substrate 160 travel along a substrate supportpath 451, and the reticle 430 travels in the opposite direction along areticle path 432 that is inclined relative to the radiation path 480 bythe tilt angle 433 that is generally slightly less than a normal angle.In one aspect of this embodiment, the tilt angle 433 can have a value ofabout 400 microradians less than a normal angle, and in otherembodiments, the tilt angle 433 can have other values. In eitherembodiment, the reticle 430 can travel along the reticle path 432 at ahigher rate of speed than the substrate support 450 travels along thesubstrate support path 451 to account for the effect of the reductionlens 440. For example, when the reduction lens 440 reduces the size ofthe image passing through the reticle 430 by a factor of four, the speedof the reticle 430 can be four times as great as the speed of thesubstrate support 450.

Because the reticle 430 is inclined at the non-normal angle 433 andmoves relative to the incoming radiation along the reticle path 432inclined at the non-normal angle 433, the focal plane of the radiationbeam changes axial position relative to the microlithographic substrate160 as the reticle 430 and the substrate support 450 move past eachother. As described above with reference to FIGS. 1-3F, an advantage ofthis arrangement is that the radiation focal plane can pass throughseveral strata within the layer 161 to more thoroughly expose the layer161.

FIG. 5 is a partially schematic illustration of a portion of anapparatus 510 that includes a substrate support 550 carrying themicrolithographic substrate 160. In a further aspect of this embodiment,the substrate support 550 travels along a substrate support path 551that is oriented approximately normal to radiation traveling along aradiation path 580 in a second direction 582. In a further aspect ofthis embodiment, the substrate support 550 carries the microlithographicsubstrate 160 at a non-normal angle 563 relative to the second direction582 of the incident radiation.

The apparatus 510 further includes a reticle 530 positioned to move inthe opposite direction as the substrate support 550. The reticle 530 ispositioned approximately normal to an incident radiation beam 528traveling in a first direction 581, and moves along a reticle path 532that is inclined at a reticle path angle 536 relative to the firstdirection 581. In one aspect of this embodiment, the value of thereticle path angle 536 and the substrate tilt angle 563 can be relatedand can both be slightly less than a normal angle. For example, thecomplement of the substrate tilt angle 563 can be less than thecomplement of the reticle path angle 536 by a factor corresponding tothe reduction factor of a reduction lens 540 positioned between thereticle 530 and the substrate support 550. In one specific embodiment,the substrate tilt angle 563 can have a value of about 100 microradiansless than a normal angle (with a complement of about 100 microradians),the reticle path angle 536 can have a value of about 400 microradiansless than a normal angle (with a complement of about 400 microradians),and the reduction lens 540 can reduce the size of an incoming image by afactor of four. In other embodiments, these angles can have differentvalues depending for example, on the power of the reduction lens 540.

An advantage of any of the embodiments described above with reference toFIG. 5 is that the microlithographic substrate 160 can pass throughradiation focused at a variety of focal planes as it moves relative tothe reticle 530. Accordingly, more than a single depth-wise plane of thelayer 161 disposed on the microlithographic substrate 160 can be exposedto focused radiation.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. For example, any of the refractiveelements described above, including the reticle, can be replaced withreflective elements that perform generally the same function.Accordingly, the invention is not limited except as by the appendedclaims.

1-31. (Cancelled).
 32. A method for exposing a radiation-sensitivematerial of a microlithographic substrate to a selected radiation,comprising: directing the radiation along a radiation path in a firstdirection toward a reticle; orienting a plane of the reticle at a firstnon-normal angle relative to the first direction; passing the incidentradiation through an aperture in the reticle and to themicrolithographic substrate along the radiation path in a seconddirection; positioning a plane of the microlithographic substrate atleast approximately normal to the second direction; moving themicrolithographic substrate relative to the radiation along a substratepath at least approximately normal to the second direction; and movingthe reticle relative to the radiation along a reticle path, the reticlepath being inclined relative to the substrate path by a secondnon-normal angle approximately equal to the first non-normal angle. 33.The method of claim 32, further comprising selecting the first andsecond non-normal angles to have a value of about 400 microradians lessthan a normal angle.
 34. The method of claim 32, further comprisingselecting the radiation-sensitive material to include a coating ofphotoresist material.
 35. The method of claim 32 wherein moving thereticle includes moving the reticle in a direction generally oppositethe motion of the microlithographic substrate.
 36. The method of claim32 wherein the microlithographic substrate has first and second fields,and wherein the method further comprises: aligning the radiation pathwith the first field; moving the reticle and the microlithographicsubstrate relative to each other while the radiation path is alignedwith the first field; repositioning at least one of themicrolithographic substrate and the radiation path relative to the otherto align the radiation path with the second field; and moving thereticle and the microlithographic substrate relative to each other whilethe radiation path is aligned with the second field.
 37. The method ofclaim 32, further comprising selecting the first direction to be atleast approximately parallel to the second direction.
 38. The method ofclaim 32, further comprising: passing the radiation through at least onereducing lens having a reduction factor; moving the microlithographicsubstrate at a first rate; and moving the reticle at a second rate thatis less than the first rate by approximately the reduction factor.
 39. Amethod for exposing a radiation-sensitive material of amicrolithographic substrate to a selected radiation, comprising:directing the radiation along a radiation path in a first directiontoward a reticle; orienting a plane of the reticle approximately normalto the first direction; passing the radiation through the reticle and tothe microlithographic substrate along the radiation path in a seconddirection; orienting the microlithographic substrate at first angleinclined relative to the second direction; moving the microlithographicsubstrate relative to the radiation along a substrate path oriented atleast approximately parallel to the first angle; and moving the reticlerelative to the radiation along a reticle path oriented at a secondangle inclined relative to the second direction.
 40. The method of claim39 wherein the radiation passes through a lens having a reductionfactor, and wherein the second angle is approximately equal to the firstangle divided by the reduction factor.
 41. The method of claim 39,further comprising selecting the first angle to have a value of about100 microradians less than a normal angle and selecting the second angleto have a value of about 400 microradians less than a normal angle. 42.The method of claim 39, further comprising selecting theradiation-sensitive material to include a coating of photoresistmaterial.
 43. The method of claim 39 wherein moving the reticle includesmoving the reticle in a direction generally opposite to the motion ofthe microlithographic substrate.
 44. The method of claim 39 wherein themicrolithographic substrate has first and second fields, and wherein themethod further comprises: aligning the radiation path with the firstfield; moving the reticle and the microlithographic substrate relativeto each other while the radiation path is aligned with the first field;repositioning at least one of the microlithographic substrate and theradiation path relative to the other to align the radiation path withthe second field; and moving the reticle and the microlithographicsubstrate relative to each other while the radiation path is alignedwith the second field.
 45. The method of claim 39, further comprisingselecting the first direction to be approximately parallel to the seconddirection. 46-76. (Cancelled).
 77. An apparatus for exposing aradiation-sensitive material of a microlithographic substrate to aselected radiation, comprising: a source of radiation positioned todirect a selected radiation along a radiation path; a substrate supporthaving a support surface positioned to support a microlithographicsubstrate in the radiation path with a surface of the microlithographicsubstrate at least approximately normal to the radiation path, whereinthe substrate support is coupled to at least one actuator to moverelative to the radiation path along a substrate support pathapproximately normal to the radiation path; and a reticle positioned inthe radiation path between the source of radiation and the substratesupport, the reticle being oriented at a first non-normal angle relativeto the radiation path, the reticle being configured to pass at least aportion of the radiation along the radiation path to the substratesupport, the reticle being coupled to at least one actuator to moverelative to the radiation path along a reticle path, the reticle pathbeing inclined relative to the substrate path by a second non-normalangle approximately equal to the first non-normal angle.
 78. Theapparatus of claim 77 wherein the first and second non-normal angles tohave a value of about 400 microradians less than a normal angle.
 79. Theapparatus of claim 77 wherein the radiation source is configured to emitradiation having a wavelength of from about 13 nanometers or less toabout 365 nanometers.
 80. The apparatus of claim 77 wherein themicrolithographic substrate has first and second fields, and wherein thereticle is configured to sequentially scan across the first and secondfields.
 81. An apparatus for exposing a radiation-sensitive material ofa microlithographic substrate to a selected radiation, comprising: asource of radiation positioned to direct a selected radiation along aradiation path; a substrate support configured to support amicrolithographic substrate in the radiation path with a surface of themicrolithographic substrate at a first non-normal angle relative to theradiation path, wherein the substrate support is coupled to at least oneactuator to move relative to the radiation path along a substratesupport path at least approximately parallel to the first non-normalangle; and a reticle positioned in the radiation path between the sourceof radiation and the substrate support, the reticle being oriented at anat least approximately normal angle relative to the radiation path, thereticle being configured to pass at least a portion of the radiationalong the radiation path to the substrate support, the reticle beingcoupled to at least one actuator to move relative to the radiation pathalong a reticle path oriented at a second non-normal angle relative tothe radiation path.
 82. The apparatus of claim 81 wherein the firstnon-normal angle has a value of about 100 microradians less than anormal angle and the second non-normal angle has a value of about 400microradians less than a normal angle.
 83. The apparatus of claim 81wherein the radiation source is configured to emit radiation having awavelength of from about 13 nanometers or less to about 365 nanometers.84. The apparatus of claim 81 wherein the microlithographic substratehas first and second fields, and wherein the reticle is configured tosequentially scan across the first and second fields.